I wonder whether the Chinese will have any "repeat capacity" in the Chang'e programme.

For example, should Chang'e 3 not survive a lunar landing, would everything rest on Chang'e 4 or would a Chang'e 3 replacement be flown, so that China (hopefully) has two successful rover missions before the pair of sample-return missions?

As the Chang'e flights become more demanding it is reasonable to expect that failures will appear in the programme.

I don't have a reference, but i remember reading somewhere that Chang'e-2 was essentially built as a spare for Chang'e-1 and once the first once flew successfully, received it's pre-planned upgrades.

If they learned anything from their success there, and from the early days of exploration technology developments, back when series numbers for probes in double digits were not uncommon, one would hope that they are building spare(s).

I don't have a reference, but i remember reading somewhere that Chang'e-2 was essentially built as a spare for Chang'e-1 and once the first once flew successfully, received it's pre-planned upgrades.If they learned anything from their success there, and from the early days of exploration technology developments, back when series numbers for probes in double digits were not uncommon, one would hope that they are building spare(s).

I remember this being said about Chang'e 2 soon after Chang'e 1 reached the Moon.

Don't forget all of the failures that the Russians had before the Luna 9 landing? And Lunas 15, 18 and 23 crash-landed. The Americans were lucky with the Surveyor 1 soft-landing, as Surveyors 2 and 4 showed.

I wonder whether the Chinese will have any "repeat capacity" in the Chang'e programme.

Why wouldn't they?

There's over a billion Chinese, you could safely assume that someoneworking for their space program would independently think of the same thing you posted. In other words? You could bet your bank account, Phil, that that contingency is already in the works over there.

What is new to me in this article is that the Chinese will not be doing a direct return to Earth from the lunar surface - as the Soviet Union did with its sample-return missions - but they plan to launch back into selenocentric orbit, perform a docking and then come back to Earth.

The unmanned rendezvous in selenocentric orbit will be a major space "first" if the Chinese pull it off: I wonder why they have chosen this approach. Maybe they are thinking of proving some technologies for a Mars sample-return mission during the 2020s using the heavy-lift launch vehicle or multiple CZ-5 launches?

Using Lunar orbit rendezvous (LOR) greatly increases the mass returned to Earth, a few hundred grams for the Russian Luna sample return missions compared to two kg for LOR. This is because you do not need to carry the 1 km/s of return propellant from Lunar orbit all the way down and back up again (a 4 km/s penalty).

Using Lunar orbit for the return also allows return from any point on the Moon. If using a single burn direct ascent like the Luna missions, you are restricted to certain areas of the Moon, I believe to be in the Eastern hemisphere.

« Last Edit: 03/21/2012 02:26 AM by Steven Pietrobon »

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Using Lunar orbit rendezvous (LOR) greatly increases the mass returned to Earth, a few hundred grams for the Russian Luna sample return missions compared to two kg for LOR. This is because you do not need to carry the 1 km/s of return propellant from Lunar orbit all the way down and back up again (a 4 km/s penalty).Using Lunar orbit for the return also allows return from any point on the Moon. If using a single burn direct ascent like the Luna missions, you are restricted to certain areas of the Moon, I believe to be in the Eastern hemisphere.

My understand is that the restriction on the Luna 15 et al sample-return mission landing site longitude was because the ascent stage did not have a pitchover capability - the implication being that with this capability you could land elsewhere on the Moon.

I would have thought that including a separate Earth-return stage in selenocentric orbit would decrease the mass of the lunar sample being brought back because of the extra equipment required for the automatic rendezvous and docking - plus the additional stage structure itself.

I thought, that doing lunar orbit automatic docking in sample return missions could mean also technology test, which can be greatly needed for manned missions. Don't know exactly why , but for me may be useful for precise testing of spacecraft and landing before actual human flight, or for orbital maneuvers without human presence like for constructing orbital station.

I thought, that doing lunar orbit automatic docking in sample return missions could mean also technology test, which can be greatly needed for manned missions. Don't know exactly why , but for me may be useful for precise testing of spacecraft and landing before actual human flight, or for orbital maneuvers without human presence like for constructing orbital station.

Docking tests with crews can be done in LEO, which is why I linked this approach to possibly technology-testing for a Mars mission.

But I still don't see why they would want to complicate and already-complex mission which only the Soviet Union has previously accomplished.

Docking tests with crews can be done in LEO, which is why I linked this approach to possibly technology-testing for a Mars mission.

But I still don't see why they would want to complicate and already-complex mission which only the Soviet Union has previously accomplished.

Yes, this make sense. But if any docking on the lunar orbit is needed - and can be done without astronauts, it could be more cost effective. It depends on Chinese lunar architecture in first years I think. For example adding new module to existing lunar orbital station, cargo flights to orbital station... I am not sure if this is real, even for first years after manned lunar landing. Later automatic dockings could be important...

So, if sample return mission is about testing docking technology too, it could mean, the Chinese lunar program plans to use it from the beginning (LOS in a few years after first manned flights?)

It depends on how difficult is to make automatic dockings in orbits further from earth for them; if it is largely more complicated they barely intend it just for robotic lunar exploration purposes and if possibly decreases lunar sample weight that could make worse scientific results than Soviet approach.